But KGIS does obtain aerial photo coverage for entire quadrants of Knox County on the same annual and cyclical basis. It is therefore possible for the aerial photo layer to be more recent than its associated digital “planimetric” layer.

So take a look at the aerial photo Map Theme to see if your house is visible there. If your house is not visible on the aerial photo layer, then it was probably built since the photography was last flown for that portion of Knox County.

To see when your area was last flown and updated, click the "Get Map Date" link in the upper right hand border of the map. This will tell you the last time the current displayed map area was flown (see Aerial Photography section) and updated (see Planimetric Data section).

a.) Property Data and Planimetric Data (e.g. buildings, fences, edge of pavement, etc.) are captured by different departments and different mapping processes. Property data is captured by the Knox County Property Assessor's Office. They digitize property data from surveyor-supplied plats, or from deed descriptions, on a daily basis. Planimetric features are maintained by KGIS on a 4-year cycle (see question #1 above) and captured from aerial photography. Since property lines are obtained from a more current, and sometimes more accurate source (surveyed plats), it is possible for them to overlap planimetric data, which is captured at best once every four years.

b.) In 1985 when the original data was captured for KGIS, property data was digitized from old hand-drawn maps and “warped” to best-fit with the aerial photography. As surrounding properties are surveyed and registered with the Knox County Property Assessor's Office, the property boundaries are adjusted as accurately as possible. Other sources for error include: incorrect or inadequate deed/plat information, software bugs, data entry errors.

For questions about property boundaries, especially related to inaccurate map depictions, please contact the Knox County Property Assessor's Office at (865) 215-2360.